home *** CD-ROM | disk | FTP | other *** search
- Path: sparky!uunet!stanford.edu!agate!usenet.ins.cwru.edu!magnus.acs.ohio-state.edu!zaphod.mps.ohio-state.edu!usc!news.service.uci.edu!unogate!mvb.saic.com!macro32
- From: REGI's <NUNEZ@esevvx.cica.es>
- Newsgroups: vmsnet.internals
- Subject: (None)
- Message-ID: <01GPZHTP9W4G0001ZZ@esevvx.cica.es>
- Date: Thu, 15 Oct 1992 17:26:00 UTC+0100
- Organization: Macro32<==>Vmsnet.Internals Gateway
- X-Gateway-Source-Info: Mailing List
- Lines: 67
-
- >X-Envelope-to: MACRO32@WKUVX1.bitnet
- >X-VMS-To: IN::"MACRO32@WKUVX1.BITNET"
-
- 1
- 12-OCT-1992 12:48:33.64
- 1 00:00:00.00
- 13-OCT-1992 12:48:33.64
- @UKCC.uky.edu:MacroMan@WKUVX1.BITNET
- gutier@SEVAXU.CICA.ES
-
- Received: from UKCC.uky.edu by ESEVVX.CICA.ES ; 9-OCT-1992 12:48:16.08
- Received: from ukcc.uky.edu by UKCC.uky.edu (IBM VM SMTP V2R2)
- with BSMTP id 3044; Fri, 09 Oct 92 07:47:08 EDT
- Received: from WKUVX1.BITNET by ukcc.uky.edu (Mailer R2.08) with BSMTP id 5377;
- Fri, 09 Oct 92 07:47:07 EDT
- Errors-To: MacroMan@WKUVX1.BITNET
- X-ListName: "VMS Internals, MACRO, and BLISS Discussions"
- <MACRO32@WKUVX1.BITNET>
- Received: from CUNYVM.BITNET (MAILER) by WKUVX1 (MX V3.1C) with BSMTP; Fri, 09
- Oct 1992 06:44:20 CDT
- Received: from CUNYVM by CUNYVM.BITNET (Mailer R2.08) with BSMTP id 2623; Fri,
- 09 Oct 92 07:41:54 EDT
- Received: from KOPC by CUNYVM.CUNY.EDU (IBM VM SMTP V2R2) with TCP; Fri, 09 Oct
- 92 07:41:31 EDT
- Received: from DECNET-MAIL (ARNE@KO) by kopc.hhs.dk (PMDF #3400 ) id
- <01GPQTVHA7W08WW0VG@kopc.hhs.dk>; Fri, 9 Oct 1992 12:40:55 +0100
- Date: 09 Oct 1992 12:40:54 +0100
- From: Arne Vajhxj <ARNE@ko.hhs.dk>
- Reply-To: MACRO32@WKUVX1.BITNET
- Subject: Re: C Language question
- To: MACRO32 <MACRO32@WKUVX1.BITNET>,
- NRA%ipg.ph.kcl.ac.uk@nsfnet-relay.ac.uk
- Message-ID: <01GPQTVHA7W28WW0VG@kopc.hhs.dk>
- X-VMS-To: KOPC::IN%"@cunyvm.cuny.edu:MACRO32@WKUVX1.BITNET"
- X-VMS-Cc: IN::"NRA%ipg.ph.kcl.ac.uk@nsfnet-relay.ac.uk"
- MIME-version: 1.0
- Content-type: TEXT/PLAIN; CHARSET=ISO-8859-1
- Content-transfer-encoding: 8BIT
-
- > Question: in C, if one declares char a[I][J], is there anything in the
- > language standard that guarantees that &a[0][0] is the first of a set of
- > I*J contiguous chars, and that a[i+1][0] is guaranteed to be the same
- > storage location as a[i][J] ).
- >
- > A friend asserts that it is, and says his experience on several systems
- > 'proves' this. My belief is that there is nothing that says this will
- > always be the case, and that the only constraint is that every valid pointer
- > a[i] will point to J chars. Which of us is right?
-
- I think your friend is rigth (a[I][J] would be I*J contigious bytes), but
- I can not prove it, but ...
-
- The arguments are:
- 1) As your friend has observed C-compilers tend to do it that way.
- 2) The creative way C lets you manipulate arrays, pointers and
- addresses must somehow assume, that they are stored contigious.
- 3) It is most efficient that way (simpler address calculations).
-
- But to be absolutely certain you will need to check the real sources:
- K&R and the ANSI specifications.
-
- Arne
-
- Arne Vajhxj local DECNET: KO::ARNE
- Computer Department PSI: PSI%23831001304030::ARNE
- Business School of Southern Denmark Internet: ARNE@KO.HHS.DK
-
-